1. Field of the Invention
The invention relates to a line layout and a line layout method and more particularly relates to a spacer self-aligned quadruple patterning (SAQP) process and a line layout.
2. Description of Related Art
Due to the decreasing sizes of semiconductor devices, exposure technology that uses extreme ultraviolet (EUV) having a short wavelength of 13.5 nm has been proposed. However, such exposure technology requires high equipment costs and is not applicable for mass production. Therefore, it is expected to use the spacer self-aligned double patterning (SADP) technology to overcome the problems of the EUV exposure technology.
The spacer self-aligned double patterning is a technique that forms spacers on the sidewall of the first mask pattern, forms the second mask pattern between the spacers, and then removes the spacers. Through self-aligned double patterning, the spacing can be reduced to half of the line pitch of the general lithography and etching process.
In addition, spacer self-aligned quadruple patterning technology has been proposed for further reducing the spacing on the basis of the self-aligned double patterning. The spacer self-aligned quadruple patterning is a technique that performs the self-aligned double patterning twice. However, the lines fabricated by the self-aligned quadruple patterning technique usually have much smaller spacing between the line ends, which may result in improper electrical connection between the lines. As an attempt to solve the above problem, currently the lithography and etching process is carried out several times in the spacer self-aligned quadruple patterning process in most cases. The lithography and etching processes effectively increase the spacing between line ends but raise the production costs and the fabrication complexity.
In view of the above, a technique that can effectively increase the spacing between line ends with fewer lithography processes is desired.